I sure would have joined this thread if I had seen it earlier, as I have been waiting too! I have one each of RIR, Australorp, Barnevelder and Silver Campine and they are about 25 weeks old now.
I kept the nesting boxes blocked off till they were about 20 weeks old, to make sure they didn't start sleeping in there. All good. I got my very first egg on Sunday 25th November - and one every day since. I posted a picture in the First Egg Countdown thread someone else mentioned earlier, as I wasn't sure who had laid it as the A'lorp and RIR eggs are similar. Most thought A'lorp but it turns out to be the RIR (Ladybird) who is a calm, authoritative, non-bully Top Chook so I am very pleased. I finally found her just before and after laying, so it is her, not Beetle the A'lorp. I read you thought your Australorps were "quite regal". Hah! My Beetle is a boisterous, greedy thing, not at all regal. I'm sure glad Ladybird keeps her calmly in check. She would have made a terrible Top Chook, I think.
Now it looks like Barnie the Barnevelder is close to lay - I just asked a question about whether they "practice" because she spent 20 minutes in the nesting box, cooing and sitting on a dummy egg. Then came back out - but no egg...... Apparently, they DO practice and I might get a nice dark brown egg from her any day now. She and Beetle do the squatting, but it hasn't been as long as Ladybird. Nor do they hold the position for very long. They both have lovely big red combs and wattles now.
Sylvia, the Silver Capmine still has quite a small and pale comb and no squatting. She loves to jump up on my lap if I sit down though!
I only put out shell grit (oyster shells) once I got the first egg. Ladybird is the only one I've seen eating it so far. The others take a look but aren't interested yet.
It is the beginning of summer here in Australia so all my girls should be laying soon. It is still so exciting waiting for the first one from each of them. Keep us posted!